In known gas bag covers, decorative elements, such as an emblem of an automotive manufacturer, ornamental rings or the like, are connected with the plastic cap by rivets. For the rivets to be passed through, the plastic cap is provided with a plurality of apertures, which may lead to a change in strength of the plastic cap.
The invention provides a gas bag cover which distinguishes itself by a simple manufacture and a consistent strength, and further provides a method of manufacturing such a gas bag cover.
According to the invention, a gas bag cover for a vehicle occupant restraint system has a plastic cap with a front face and a rear face facing a gas bag, and a decorative element provided on the front face. The decorative element is welded to the plastic cap.
The gas bag cover according to the invention distinguishes itself by a simple manufacturability, low production costs and a uniform strength.
Preferably, the decorative element is made of plastic, in particular of the same plastic as the plastic cap. This facilitates welding the decorative element to the plastic cap. In addition, especially with a decorative element of large dimensions, a flexible material is particularly useful with a view to a possible activation of the restraint system.
As an alternative, the decorative element may have an outer coating made of plastic, which surrounds a metal core, for example. In this case, the outer coating is preferably made of the same plastic material as the plastic cap.
Owing to the attachment of the decorative element by welding, the plastic cap does without any apertures in the region of the decorative element.
According to a preferred embodiment, the decorative element is formed by a closed curve, in particular a ring, an oval or a trapezoid. Of course, an open curve is also conceivable. Inside and outside of the decorative element, the material of the plastic cap is visible on the front face facing the vehicle occupant.
The external dimensions of the decorative element may correspond to at least a third of the external dimensions of the plastic cap; the decorative element thus has comparatively large dimensions in relation to the overall size of the gas bag cover.
An especially sturdy attachment of the decorative element is obtained in that the front face of the plastic cap has a recessed portion in which the decorative element is arranged. The top face of the decorative element facing the vehicle occupant may then be flush with, or project relative to, the front face of the plastic cap.
To facilitate a precise positioning of the decorative element, both the plastic cap and the decorative element should each have an integrally molded extension which extends into and, as it were, defines the welding zone. The two extensions are then welded directly to each other.
In its visible portion, the decorative element may have an external color which is different from that of the plastic cap on the front face thereof, something which contributes to a visually especially appealing gas bag cover.
A particularly high-quality configuration is obtained if the decorative element has a coating, preferably a metallic coating.
At least on its front face, the plastic cap itself may also have a plurality of regions having different colors. In this case, a parting line between two regions having different colors can be concealed by the decorative element.
According to a second aspect of the invention, a method of manufacturing a gas bag cover is provided, which comprises the following steps. First, a plastic cap and a decorative element, preferably likewise made of plastic, are produced as separate components, for example in a foaming or injection molding process. The decorative element and the plastic cap are then welded to each other. The method according to the invention is simple and therefore cost-effective, and permits a color design of the decorative part that is independent of that of the plastic cap. In addition, when designing the inner face of the plastic cap, there is no need to allow for sufficient free space for riveting tools or the like since rivets for attachment of the decorative element may be dispensed with.
The decorative element is connected with the plastic cap by heated tool welding, for example. Furthermore, ultrasonic welding also constitutes a suitable method.
In accordance with one variant of the method, the decorative element or the plastic cap or both components are coated prior to the welding step, such as with a paint or varnish or by powder coating. As an alternative, the components may be produced to have the desired surfaces from the start, such as by injection molding.
In this connection it should be noted that all of the further configurations mentioned with respect to the gas bag cover can also be employed to advantage in the method according to the invention.